Estha, which is short for Esthappen Yako, is Rahel's twin brother. He is a serious, intelligent, and somewhat nervous child who wears "beige and pointy shoes" and has an "Elvis puff." His experience of the circumstances surrounding Sophie Mol's visit is somewhat more traumatic than Rahel's, beginning when he is sexually abused by a man at a theatre. The narrator stresses that Estha's "Two Thoughts" in the pickle factory, which stem from this experience (that "Anything can happen to Anyone" and "It's best to be prepared") are critical in leading to his cousin's death.
Estha is the twin chosen by Baby Kochamma, because he is more "practical" and "responsible," to go into Velutha's cell and condemn him as their abductor. This trauma, in addition to being shipped (or "Returned") to Calcutta to live with his father, contributes to Estha becoming mute at some point in his childhood. Estha never went to college and acquired a number of habits, such as wandering on very long walks and obsessively cleaning his clothes. He is so close to his sister that the narrator describes them as one person, despite having been separated for most of their lives. He is repeatedly referred to as "Silent" in the book.
Rahel is the partial narrator of the story, and is Estha's younger sister by eighteen minutes. As a girl of seven, her hair sits "on top of her head like a fountain" in a "Love in Tokyo" and she often wears red-tinted plastic sunglasses with yellow rims. An intelligent and starightforward person who has never felt socially comfortable, she is impulsive and wild, and, by implication, treated as somehow lesser than her brother by all but the Untouchable carpenter Velutha. In later life, she becomes something of a drifter, several times the narrator refers to her "Emptiness." After the incident which forms the core of the story, she remains with her mother, later training as an architectural draughtsman and engaging in a failed relationship with a European, elements of which parallel the author's own life story.
Ammu is Rahel and Estha's mother. She married their father (referred to as Baba) only to get away from her family. He was an alcoholic, and she divorced him when he started to be violent towards her and her children. She went back to Aymanam, where people avoid her on the days when the radio plays "her music" and she gets a wild look in her eyes. When the twins are seven, she has an affair with Velutha, a Paravan (Untouchable). This relationship is the cataclysmic event in the novel. She is a strict mother, and her children worry about losing her love.
Velutha is a Paravan, an Untouchable, who is exceptionally smart and who works as a carpenter for the Ipe family's pickle factory. His name means white in Malayalam, because he is so dark. He returns to Aymanam to help his father, Vellya Paapen, take care of his brother who has suffered from an accident. He is an active member of the Marxist movement. Velutha is extremely kind to the twins, and has an affair with Ammu for which he is brutally punished.
Chacko is Estha and Rahel's maternal Uncle. He is four years older than Ammu. He meets Margret Kochamma in his final year at Oxford and marries her afterwards. They have a daughter Sophie Mol, whose death at Ayemenem becomes central to the story.
Baby Kochamma is the twins' maternal great aunt. She is of petite build as a young woman but becomes enormously overweight with 'a mole on her neck' by the time of the incident. She maintains an attitude of superiority due to her education as a garden designer in the US and her burning, unrequited love for an Irish Catholic priest which forms the only meaningful event in her life. The emptiness and failure of her own life sparks a bitter spite for the children of her sister driven by her prudish code of conventional values which ultimately condemn the twins, the lovers and herself to a lifetime of misery.